1. Field of the Invention
The present invention relates to a drive unit.
2. Description of the Prior Art
A vibratory actuator has been conventionally known which is for use in various electronic devices or other devices and includes a piezoelectric element (electromechanical transducer) (see, for example, Patent Document 1). This piezoelectric element is obtained by alternately stacking piezoelectric bodies and electrodes. For the vibratory actuator, the piezoelectric element is vibrated by applying voltages to the electrodes, thereby moving a movable body.    Patent Document 1: Japanese Laid-Open Publication No. 2006-115583
To achieve highly accurate positioning of a movable body, the movable body may be switched from a coarse motion mode in which the movable body is moved at high speed to a fine motion mode in which the movable body is finely moved. As a driving method used in this fine motion mode, there is a so-called burst driving method.
However, in the burst driving method, vibration of a piezoelectric element is initiated and stopped at predetermined intervals (i.e., burst intervals, for example, of 100 Hz). Consequently, noise is generated.